Control means for electrical circuits and the like



B. S. SEDLEY Oct. 16, 1962 CONTROL MEANS FOR ELECTRICAL CIRCUITS AND THE LIKE 2 Sheets-Sheet 1 Original Filed July 1, 1959 INVENTOR. 23 BRUCE $.SE'DLEY BY am an ATTORNEY TAPE PLAY BACK MACHINE B. s. SEDLEY 3,059,069

ICAL CIRCUITS AND THE LIKE Oct. 16, 1962 CONTROL MEANS FOR ELECTR 2 Sheets-Sheet 2 Original Filed July 1 15k NVENTOR.

ATTORNEY.

BRUCE 5. 5501.5)

tare

This invention relates to improvements in control means for electrical circuits. More particularly, it relates to a novel electrical switch of the lock-and-key type. This case is a continuation of application Serial No. 824,289 filed on July 1, 1959, now abandoned.

An example or two will give an idea of how the invention is used. At a childrens park in Oakland, California, a series of sets illustrates a series of nursery rhymes. At each nursery-rhyme set a metal standard supports what looks like a large book about the size and thickness of a telephone book. All that can be seen on the outside of this book is a keyhole and the title of the nursery rhyme, but inside the book is a loudspeaker, and the keyhole leads to a special lock embodying the principles of this invention. At the entrance to the park, a mechanical vending machine sells plastic keys embodying the principles of this invention. Any of these keys will fit all the locks in the park. When a child buys one of these keys he can unlock every book in the park. He does this by putting the key in the keyhole and turning the key about 180.

What happens, then, is that the key operates the plungers for two microswitches that are electrically connected in series. Turning the key closes the switches and actuates an electrical message-repeater-a type of tape-playback machine. This message-repeater then plays a recorded message through the loudspeaker inside the book, and the message may be heard by anyone standing directly outside the book. The message may, for example, be a musical version of the nursey rhyme that is represented by the set, or it may tell a story.

The message-repeater need not be in the book or even very close to it, though preferably the connecting wires should not be too long. But the point is that a child who has the key can hear all the messages in the park, and one who doesnt have the key cannot hear them except by tagging along with one who has.

The same thing can be done in 2005, museums, nature walks-wherever a spoken, audible description of what is being seen is desired. And it has other uses, many of them obvious to a skilled man in this field. For example, a slide projector may replace the message-repeater.

One advantage of the system of this invention is that it does away with the nickel-in-the-slot type of operation at each loudspeaker. Only one vending machine is needed; the one at which the keys are sold. In Oakland, each key is sold in a box, complete with a gold chain and printed tag that explains its use and lists the different sets where there are locks operated by the key. The children are encouraged to use the key to hear all the stories and then to take the key home and be sure to bring it back with them the next time they visit the park. They use it again and again, and the key will always operate all the books in the park. That encourages re-attendance at the park, where admission is charged, and encourages many others to visit the park. It also encourages everyone to have his own key.

From the foregoing, it will be seen that one of the main objects of the invention is to provide a customeroperated electrical starting-switch arrangement which is feasible for use by many different customers.

Another object of the invention is the provision of a 3,059,069 Patented Oct. 16, 1962 novel lock-and-key arrangement, for there are special problems where such use is made of it.

A further object of the invention is to provide a lockand-key type of electrical switch that is as simple and as nearly foolproof as is possible.

Another object of the invention is to provide a relatively tamper-proof switch arrangement. In the present invention, this is done by using a plurality of electric switches in series, each having its own switch plunger. This makes it impossible, or at least quite impractical, to depress both switch plungers by use of a nail or other article different from the actual key itself. Usually two switches are enough, but more may be used if desired.

Another object of the invention is to provide a key especially well adapted for the purpose and for use as a souvenir article.

Another object of the invention is to provide an attractive system for encouraging children or adults to patronize an explanation system, or story, or the like accompanying an exhibit.

Another object is to provide a novel mounting and assembly of the lock and support.

Other objects and advantages of the invention will appear from the following description of a preferred embodiment thereof.

In the drawings:

FIG. 1 is a View in perspective of a book-like installation incorporating an electric switch arrangement embodying the principles of this invention. A key is shown partially inserted into the opening.

FIG. 2 is a view partly in perspective and partly in diagrammatic form, showing the book installation of FIG. 1 with its switch connected to a tape playback machine and the tape playback machine connected to a loudspeaker in the book installation.

PEG. 3 is an electrical diagram of a portion of the circuit of FIG. 2, showing the plurality of switches in series with each other and with the tape playback machine.

FIG. 4 is an enlarged view in perspective of the lockand-key arrangement of this invention, showing the electrical switch element adjacent the lock and the key outide the lock. To show the parts more clearly, the lock and key have been shown upside-down.

FIG. 5 is a perspective view of the key in PEG. 4, shown upside-down.

FIG. 6 is a perspective view of the mounting assembly for the lock of FIG. 5.

FIG. 7 is a view in elevation and in section of the lock of PEG. 4, with the lock rotated FIG. 8 is a View in elevation and in section similar to FIG. 7, but showing a key shank inserted therein preparatory to operation and showing portions of the mounting plates for the lock.

FIG. 9 is a View in section taken along the line 9-9 of FIG. 7.

FIG. 10' is a view taken in section along the line lit-10 of FIG. 8.

EEG. 11 is a plan view of one-half of the switch-body, showing the receptacle arrangement and the actuating portions thereof, and portions of the mounting plates and screws.

FIGS. 1-3 illustrate a typical installation of the invention, wherein a novel key 15 is used in a novel lock 16 to actuate an electrical circuit incorporating a message-repeater 17 and a loudspeaker 18. Here, the lock 16 is mounted in a book-like housing 20, and a faceplate 21 for the lock 16 lies outside the front face 22 of the book 20. The lock 16 supports a pair of switches 23' and 24 (FIG. 2). More switches may be used if desired, the key and lock being modified accordingly, but two are normally suflicient and fewer are too few.

The loudspeaker 18 may be supported by the housing 20, or elsewhere if desired; if supported by the housing 20, slits 19 allow passage of the sound. The repeater 17 is usually supported elsewhere. It is connected to the switch 23 by a wire 25 and to the switch 24 by a wire 26 (see FIGS. 2 and 3). The switches 23 and 24 are connected together by a wire 27, so that they are in series. Wires 28 and 29 connect the loudspeaker 18 to the repeater 17 (FIG. 2). A suitable electric cord 30 may connect the repeater 17 to a suitable power source, such as A.-C. current.

When the key 15 is inserted in the lock 16 and turned approximately 180, the key 15 actuates the lock 16 to close both the switches 23 and 24. When and only when this happens, the repeater 17 is actuated to send its message to the loudspeaker 13, the repeater including not only a tape cartridge and playback head but also an amplifier.

As indicated in FIGS. 1, 2 and 6, the annular faceplate 21 fits over the box face 22 in line with an opening therethrough. Four threaded studs 32 extend rearwardly from the rear side of the faceplace and pass through bolt holes (not shown) in the face 22. A pair of dual Washers 33 fit against the rear side of the face 22 and are held in place by nuts 34, thereby securing the faceplate 21 securely to the box 20. The lock 16 is provided with a projecting ridge 35 that fits into a slot 36 in the plate 21, thereby being locked thereto against relative rotation. A rear lock plate 37 with an opening 38 engages the rear face of the lock 16, around a projecting rim 39, and is bolted to the studs 32, the pressure against the lock holding it securely in place.

FIGS. 411 show the lock 16 and key 15 in more detail. The body of the lock 16 is made in two pieces 44'! and 41, so that it can easily be assembled or taken apart by inserting or removing some screws 42. Recesses 43 may be provided to facilitate disassembly, by prying with a screwdriver. When assembled, the lock body 40, 41 is rectangular in cross-section and has a cylindrical keyhole 44 that goes all the way through from one end to the other. The lock 16 is less than half the thickness of the box 20. The lock portion 41 is a simple piece that completes the body and supplies half the keyhole 44 but has no moving parts. Registration pins 45 facilitate assembly.

The lock body portion 40 supports the switches 23 and 24 and carries the working parts of the lock 16. Each switch 23, 24 has an operating lever 46, 47, respectively operated by a spring-mounted plunger 48, 49'. The plungers 48, 49 are axially aligned in the keyhole 44, project radially into it, and are radially movable. When the plungers 48, 49 are substantially flush with the keyhole wall 44, they actuate their respective switches 23 and 24.

There are guide pins 50, 51, one associated with and axially aligned with each switch-plunger 48, 49 and, like them, projecting radially into the keyhole 44. They are held stationary in the body portion 40 by set-screws 52. Similarly, the plungers 48, 49 may be spring-mounted (by springs 50a and 51a) slidably in guide studs 53 that are held by set-screws 54 (see FIG. 9) in the body member 40 at a depth equal to that of the guide pins 550, 51.

Between the guide pin 50 and the faceplate end of the keyhole 44 is a fiat plate 55 that provides the ridge 35 and also keyway 56, an axially extending radial projection, axially in line with the plungers 48, 49 and guide pins 0', 51. The keyway plate 55 may be retained in place in a slot 57 in the body 40 by a through-screw 58 and a set-screw 59 that engages one face of the plate 55'. The pins 45 mate in registration hole 45a in the body 40.

Since the keyway 56 and guide pins '54, 51 are readily removable, the lock 16 may be varied by replacing any or all of them by members of different length, to require a different key at a different installation. Also, the

holes for the pins and plungers may be bored at different locations.

The key 15 has a handle of) and a generally cylindrical shank 61. The handle dtl is preferably flat and has a stop member 62 that engages a stop member 63 on the faceplate 21 to stop the key 15 from rotating beyond a certain amount, preferably The shank 61 has a groove 64 that extends axially from a free end 65 to near the handle 61!), where it stops at an end wall 66, thereby limiting insertion of the key to the right depth.

The groove 64 has an arcuate bottom wall 67 and a radial wall 6%; that extends the full length of the groove 64 on one side of the bottom wall 67. On the other side of the groove 64, the key shank 61 has a series of sectors comprising stop bands, cams, and key slots. There are cams 7%, 71 one for each switch plunger 48, 49, each cam '70, 71 being a curved segment (preferably 186") of gradually increasing radius, leading from said bottom wall 67 to the full radius of the shank 61. For each guide pin 5%, 51 there is a key-slot '72, 73, preferably of 180, each with a bottom wall 74 the same radius as the bottom wall 6-7, with radial sidewalls '75 and an end wall 76 that lies at the same angle of rotation from the groove 64- as the end of the cams 7th, 71. There is a similar slot 77 for the keyway 56, different only as to length. Between the guide pins, keyways, etc., and at the free end 65, there are stop bands 78, wherein the groove 64 is narrow, preventing the key 15 from turning if the stop bands 78 engage a keyway or guide pin.

The lock 16 is normally made from brass, but the keys 15 are preferably made from a lightweight but strong plastic, such as butyrate. In a typical key 15, the shank 61 is about 7 in diameter, the groove 64 is /8 deep and /8 wide. The keyway 56 and keyway groove 77 are about /8 long.

in operation, the key 15 is inserted into the lock 16 and turned. it can be inserted in only one waywhere the groove 64 permits passage past the keyway 56 and the guide pins 58 and 51. The wall 66 stops insertion at exactly the right place; then, and then only, the key 15 can be turned, and it can be turned only in one direction and only a limited amount, preferably 180. Then the stops 62 and 63 prevent further turning, as do the walls 76.

The main purpose of the guide pins 56, 51 is to protect the plungers 4E 49 of the microswitches 23, 24. Without the guide pins 5t 51, a nail or some similar foreign object could conceivably join the microswitches 23, 24 and someone without a key could listen. But with two switch plungers 48, 49 and a guide pin 50, S1 protecting each plunger, it is practically impossible to actuate the device without a key 15.

When the key 15 is turned, it operates the plungers 48, 49 and closes both the switches 23 and 24 simultaneously, thereby actuating the message-repeater 17.

Preferably, the rear end of the keyhole 44 has a tapered or enlarged opening 89, so that if a key shank 61 is broken oil in the lock 16 it can be removed by pliers without having to take the lock apart. Also, since the lock 16 is less than half the frontto-rear dimension of the box Ell, a key 15 which happens to break in the lock 16 before being turned can simply be pushed out the rear end 81) by another key 15.

To those skilled in the art to which this invention relates, many changes in construction and widely differing embodiments and application of the invention will suggest themselves without departing from the spirit and scope of the invention. The disclosures and the description herein are purely illustrative and are not intended to be in any sense limiting.

I claim:

1. A key-operated electric switch assembly, including in combination: a lock assembly having a keyhole with an inlet end, a plurality of axially aligned radially movable spring-mounted switch plungers normally projecting radially into said ke hole, a plurality of stationary guide pins axially aligned withsaid switch plungers, one closely adjacent each said switch plunger, between said switch plunger and said inlet end and projecting radially into said keyhole and acting to prevent simultaneous movement of said plungers by a nail-like member that lock pickers might insert into said keyhole, and a keyway comprising an elongated member axially aligned with said plungers and guide pins and projecting into said keyhole and lying closer to said inlet end than said guide pins; an electrical circuit; a plurality of electric switches in said circuit in series with each other, each operated by radially outward movement of one said switch plunger, all said switches having to be closed before electrical current can flow through said circuit; and a key, comprising a handle and a shank having a free end and insertable in said keyhole, said key shank having an axially extending groove enabling its passage along said keyway and guide pins; a series of arcuate sectors leading from said groove, said sectors comprising cams for operating said plungers and slots enabling rotation relative to said guide pins, said key when inserted and turned actuating said switches by operating said plungers.

2. In an electric switch operated by insertion and turning of a key, a lock assembly comprising a body with a generally cylindrical keyhole having an inlet end, a plurality of axially aligned radially movable spring-mounted switch plungers normally projecting radially into said keyhole, a plurality of stationary guide pins axially aligned with said switch plungers, one closely adjacent each said switch plunger between said switch plunger and said inlet end and projecting radially into said keyhole substantially the same distance that said switch plungers normally project to prevent picking of said lock, and a keyway comprising an elongated member axially aligned with said plungers and guide pins and projecting into said keyhole substantially the same distance as they, said keyway lying closer to said inlet end than said guide pins and aiding in preventing picking of said lock.

3. A key for insertion in a key-operated electric switch assembly and operation of said assembly by rotation therein, comprising a handle and a generally cylindrical shank connected to said handle at one end and having a free end, said key shank having an axially extending groove open at said free end and stopped near said handle end, with a bottom wall, a continuous radial wall on one side and on the other side a series of sectors comprising stop bands defined by an axial wall, cams defined by a curved segment of smoothly increasing radius leading from the groove bottom wall out to the full radius of said shank, and slots with a bottom wall the same depth as said groove and opening thereinto with arcuately extending radial walls and end walls axially aligned, the portions of said cams at substantially the full radius of said shank.

4. A key-operated electric switch assembly, including in combination: a lock assembly having a generally cylindrical keyhole, a faceplate at one end of said keyhole fiaving a stop means thereon, a plurality of axially aligned radially movable switch plungers, spring means normally projecting each said plunger radially into said keyhole, a plurality of stationary guide pins axially aligned with said switch plungers and each positioned closely adjacent one said switch plunger on the side thereof closer to said faceplate and projecting radially into said keyhole substantially the same distance as said switch plungers, each said guide pin being spaced away from all other said switch plungers, and a keyway comprising an elongated axially extending radial projection axially aligned with said plungers and guide pins and substantially the same height whereas and extending from adjacent said faceplate to a point spaced from the guide pin closest to said faceplate; a plurality of electric switches in electrical series with each other and operated by radially outward movement of said switch plungers, so that all said switches must be closed for operation of the series arrangement thereof; and a key, comprising a flat handle with stop means thereon engageable with said faceplate stop means after said key has been inserted and turned and a generally cylindrical shank connected to said handle at one end and having a free end and insertable in said keyhole, said key shank having an axially extending groove open at said free end and stopped near said handle end, with a bottom axial wall, an axially extending radial wall on one side of said bottom wall lying substantially perpendicular to the plane of said handle and on the other side a series of sectors comprising stop bands defined by an axial wall, cams defined by a 180 cylindrical segment of smoothly increasing radius leading from the groove bottom wall out to the full radius of said shank, and 180 arcuate slots with a bottom wall the same depth as said groove and opening thereinto with arcuately extending radial walls and end walls axially aligned with the portions of said cams at substantially the full radius thereof, said key having a said cam for each said switch plunger, for operation thereof, a said slot for each said guide pin, and a said slot for said keyway, with said bands for the portions where said lock has no keyway, guide-pin, or cam, whereby said key, when inserted into said lock, can be turned about 180 until said stop means or said handle engages said stop means on said faceplate, but can be turned only after full insertion thereof, and whereby said switch plungers cannot be simultaneously depressed without a said key.

5. In a key-operated electric switch actuated by insertion and subsequent rotation of a key, a lock assembly having a two-piece body defining a generally cylindrical keyhole extending all the way therethrough and open at both ends, and a faceplate at one end of said keyhole, one piece of said body having a plurality of axially aligned radially movable switch plungers, spring means for each said plunger normally projecting them radially into said keyhole, a plurality of stationary guide and guard pins axially aligned with said switch plungers and each positioned closely adjacent one said switch plunger on the side thereof closer to said faceplate and projecting radially into said keyhole substantially the same distance as said switch plungers to prevent picking of said lock, each said guide pin being spaced away from all other said switch plungers, and a keyway comprising an elongated axially extending radial projection axially aligned with said plungers and guide pins and substantially the same height thereas and extending from adjacent said faceplate to a point spaced from the guide pin closest to said faceplate; a plurality of electric switches connected electrically in series with each other and mounted on said one piece and operated by radially outward movement of switch plungers, so that all said switches must be closed for operation of the series arrangement thereof; and screws holding said pieces together for easy disassembly for removal of a broken key.

6. A key for insertion and turning in an electric switch, comprising a flat handle and a generally cylindrical shank connected to said handle at one end and having a free end and an axially extending insertion-enabling groove open at said free end and stopped near said handle end, with a bottom axial wall, an axially extending radial wall on one side of said bottom wall substantially perpendicular to the plane of said handle, and on the other side a series of sectors comprising stop bands defined by an axial wall, cams defined by a 180 cylindrical segment of smoothly increasing radius leading from the groove bottom wall out to the full radius of said shank, so that on turning the key a cam action is obtained and 180 slots with a bottom wall the same depth as said groove and opening thereinto with arcuately extending radial walls and end walls axially aligned with the portions of said cams lying at substantially the full radius thereof.

7. A key-operated electric switch assembly, including in combination: a lock assembly having a generally cylindrical keyhole, a faceplate at one end of said keyhole, a

plurality of axially aligned radially movable springmounted switch plungers normally projecting radially into said keyhole, a plurality of stationary guide and guard pins axially aligned with said switch plungers, one closely adjacent each said switch plunger between said switch plunger and said faceplate and projecting radially into said keyhole substantially the same distance that said switch plungers normally project to prevent picking of said lock, and a keyway comprising an elongated member axially aligned with said plungers and guide pins and projecting into said keyhole substantially the same distance as they, said keyway lying between said faceplate and the guide pin closest to said faceplate; an electrical circuit; a plurality of electric switches in said circuit in series with each other, each operated by radially outward movement of one said switch plunger, all said switches having to be closed before electrical current can flow through said circuit; and a key, comprising a handle and a generally cylindrical shank connected to said handle at one end and having a free end and insertable in said keyhole, said key shank having an axially extending groove open at said free end and stopped near said handle end, enabling insertion along said keyway, said guide and guard pins, and said plungers, with a bottom wall, a continuous radial wall on one side and on the other side a series of sectors comprising stop bands defined by an axial wall, cams defined by a curved segment of smoothly increasing radius leading from the groove bottom wall out to the full radius of said shank for moving said plungers when said key is turned, and slots with a bottom wall the same depth as said groove and opening thereinto with arcuately extending radial walls and end walls axially aligned with the portions of said cams at substantially the full radius of said shank, said key having a said cam for each said switch plunger, for operation thereof when said key is rotated, a said slot for each said guide pin so as to permit rotation of said key relative to said guide pin, and a said slot for said keyway so as to permit rotation of said key relative to said keyway, with said bands for the portions where said lock has no keyway, guidepin, or cam, whereby said key, when inserted into said lock, can be turned only after full insertion thereof, and whereby said switches cannot be simultaneously depressed without a said key being both inserted and turned.

8. A key-operated electric switch assembly, including in combination: a lock assembly having a generally cylindrical keyhole, a faceplate at one end of said keyhole, a plurality of axially aligned radially movable switch plungers each having spring means normally projecting them radially into said keyhole, a plurality of stationary guide pins axially aligned with said switch plungers and each positioned closely adjacent one said switch plunger on the side thereof closer to said faceplate and projecting radially into said keyhole substantially the same distance as said switch plungers, each said guide pin being spaced away from all other said switch plungers and a keyway comprising an elongated axially extending radial projection axially aligned with said plungers and guide pins and substantially the same height thereas and extending from adjacent said faceplate to a point spaced from the guide pin closest to said faceplate; a plurality of electric switches in series with each other and operated by radially outward movement of switch plungers, so that all said switches must be closed for operation of the series arrangement thereof; and a key, comprising a handle and a generally cylindrical shank connected to said handle at one end and having a free end and insertable in said keyhole, said keyshank having an axially extending groove open at said free end and stopped near said handle end, with a bottom axial wall, a radial wall on one side of said bottom wall and on the other side a series of sectors comprising stop bands defined by an axial wall, cams defined by cylindrical segment of smoothly increasing radius leading from the groove bottom wall out to the full radius of said shank, and slots with a bot- 8, tom wall the same depth as said groove and opening thereinto with arcuately extending radial walls and end walls axially aligned with the portions of said cams that are at substantially the full radius thereof, said key having a said cam for each said switch plunger, for operation thereof, a said slot for each said guide pin, and a said slot for said keyway, with said bands for the portions where said lock has no keyway, guide-pin, or cam, whereby said key, when inserted into said lock, can be turned only after full insertion thereof, and whereby said switch plungers cannot be simultaneously depressed without a said key.

9. A key-operated electric switch assembly and mounting, including in combination: a housing having a front wall with a hole therethrough; a face plate on the front of said front wall surrounding and extending into said hole and having a central opening and a slot extending radially from said slot on the rear of said plate; a lock body in said housing behind said front wall in line with said central opening, having a keyhole with an inlet end and a rear end, both defined by projecting annular rims, the rim of said inlet end fitting snugly in the opening of said face plate, a plurality of axially aligned radially movable spring-mounted switch plungers normally projecting radially into said keyhole, a plurality of stationary guide pins axially aligned with said switch plungers, one closely adjacent each said switch plunger, between said switch plunger and said inlet end and projecting radially into said keyhole, and a keyway comprising an elongated flat member axially aligned with said plungers and guide pins and projecting radially into said keyhole at said inlet end and projecting axially from said inlet end into the slot of said face plate; studs projecting rearwardly from said face plate through said front wall; Washers and bolts on said studs tightening said face plate to said front wall; a rear plate fitting around the rear rim and against said body; an electrical circuit; a plurality of electric switches in said circuit in series with each other, each operated by radially outward movement of one said switch plunger, all said switches having to be closed before electrical current can flow through said circuit; and a key, comprising a handle and a shank having a free end and insertable in said keyhole, said key shank having an axially extending groove enabling its passage along said keyway and guide pins; a series of arcuate sectors leading from said groove, said sectors comprising cams for operating said plungers when said key is rotated, and slots enabling rotation relative to said guide pins, said key and said face plate having cooperative stop means, one on the handle of said key, the other projecting from said face plate to limit the turning of said key in said lock.

10. The device of claim 9 wherein the depth of said box is twice the length of said key shank, so that a broken key shank can be pushed out the rear of said lock by another key.

11. A key-operated electric switch assembly and mounting, including in combination: a housing having a front wall with a hole therethrough; a face plate on the front of said front wall surrounding and extending into said hole and having a central opening and a slot extending radially from said slot on the rear of said plate; a lock body in said housing behind said front wall in line with said central opening, having a keyhole with an inlet end and a rear end, both defined by projecting annular rims, the rim of said inlet end fitting snugly in the opening of said face plate, a plurality of axially aligned radially movable spring-mounted switch plungers normally projecting radially into said keyhole, a plurality of stationary guide pins axially aligned with said switch plungers, one closely adjacent each said switch plunger, between said switch plunger and said inlet end and projecting radially into said keyhole for preventing picking of said lock, and a keyway comprising an elongated flat member axially aligned with said plungers and guide pins and projecting radially into said keyhole at said inlet end and projecting axially from said inlet end into the slot of said face plate; studs projecting rearwardly from said face plate through said front wall; washers and bolts on said studs tightening said face plate to said front wall; a rear plate fitting around the rear rim and against said body; an electrical circuit; a plurality of electric switches in said circuit in series with each other, each operated by radially outward movement of one said switch plunger, all said switches having to be closed before electrical current can flow through said circuit.

12. A key-operated electric switch assembly and mounting, including in combination: a housing having a front wall with a hole therethrough; a face plate on the front of said front wall surrounding and extending into said hole and having a central opening and a slot extending radially from said slot on the rear of said plate; a lock body in said housing behind said front wall in line with said central opening, having a keyhole with an inlet end and a rear end, both defined by projecting annular rims, the rim of said inlet end fitting snugly in the opening of said face plate, and a keyway comprising an elongated flat member projecting radially into said keyhole at said inlet end and projecting axially from said inlet end into the slot of said face plate; studs projecting rearwardly from said face plate through said front Wall; washers and bolts on said studs tightening said face plate to said front wall; and a rear plate fitting around the rear rim and against said body.

References Cited in the file of this patent UNITED STATES PATENTS 2,080,684 Zalkind Mar. 18, 1937 2,602,85'1 Barton June 8, 1952 2,637,844 Thompson May 15, 1953 2,909,761 Rockola Oct. 20, 1959 

